Lubricating oil and method of producing same



Patented Jan. 14, 1936 UNITED STATES LUBRICATING OIL AND METHOD OF PRODUCING SAME Erwin R. Lederer, Fort Worth, Tex.

No Drawing. Application May 4, 1931, Serial No. 535,080

1 Claim.

This invention relates to an improved lubrieating oil produced from unblended parafiin base stock having a low cold test and being adapted without modification for both summer and 5 winter use and to a method of producing the same. The application is a continuation in part of my copending application, Ser. No. 334,607, filed Jan. 23, 1929.

It is generally conceded that parafiin base oils 10 are best for lubricating purposes as such oils continue to supply the desired lubricating film in automotive engines and machines even when the latter are heated up to relatively high degrees. Parafiin base oils as heretofore produced have, however, had the disadvantage of congealing or failing to flow at temperatures approaching zero Fahrenheit because of the previous impossibility of commercially fully dewaxing paraffin'base oils. I have been able to fully dewax paraflin base lubricating oils and am able to produce a fully v,dewaxed unblended paraflin base oil which will be free flowing at temperatures below its cold .test and which, in viewof its lubricating propertiesat high temperatures as well, can be used for both summer and winter driving conditions or for aeroplane work, eliminating the necessity for producing and marketing two grades of lubricating oil for these diiferent conditions.

Scientific and performance tests have shown that paraffin base lubricating oils having a lower temperature coeflicient of viscosity will stand high operating temperatures better than the asphalt base oils which have a tendency to break up under high operating temperatures. It is also recognized that the use of unblended lubricating oils having hydrocarbons in the natural order of their occurrence in the crude oil provide a more stable oil, better adapted for use at high temperatures than the blended and mixed 4 oils which have constituents vaporizing through a wide range of temperatures.

I have been able to produce a paraffin base unblended, unmixed, straight-run lubricating oil with the viscosity of from 50" at 210 F. to 200" 5 at 210 F. Saybolt Universal viscosimeter having ;50 .tofore been produced and satisfied in many ways the ideal standard for a universal summer and winter lubricating oil which has been set by the aeroplane and automotive lubrication engineers. Being a paraifln base lubricating 011, this new oil provides for better lubrication at high tem- 5 peratures, and as the oil is unmixed. or unblended parafiin base, there are no light ends to distill off or be destroyed by the high temperature. As it is fully dewaxed, it is free flowing and can be pumped under normal pump pressures of m from '7 to lbs. at temperatures even as low as minus 40 F. and therefore provides for proper lubrication at low temperatures. I have, therefore, produced a lubricating oil which is superior at all temperatures to the normal lubricating oils and may be used for both summer and winter driving and for aeroplanes in which wide variations in temperature are experienced in a relatively short period of time in altitude flights, without the necessity of carrying two grades of oil.

The lubricating oil forming the subject matter of this invention, therefore, has the following characteristics 1. It is an unblended paraffin base lubricating oil.

2. It is completely dewaxed, i. e., free from wax for commercial purposes.

3. Its viscosity on the Saybolt Universal viscosimeter is from 50" at 210 F. to 200" at 210 F. but preferably from 60" at 210 F. to 200 at 210 F.

4. It will flow at pressures from 7 to 10 lbs. absolute at temperatures from plus 20 F. to minus 40 F.

5. It retains its lubricating properties at higher temperatures and being unblended, there is no tendency of any lighter fractions to distill over at higher operating temperatures.

It has in the past been considered impossible to fully dewax heavy paraflin base cylinder and bright stocks and distillates, either by the cold settling method, by filtration or by centrifuging. The cold test of cylinder stock, bright stock and distillates manufactured from paraffin base crudes has been so far anywhere from plus 20 F. to 45 F., and paraffin base lubricating oils of cold test above 20 F., when lowered to a temperature below 20 F., congeal and solidify so as to make it impossible to pump the same through the normal lubricating channels of the engines.

With the fully dewaxed oil, however, which I am able to produce according to the present invention, having a cold test of from zero or below to 10 F., the complete removal of the wax permits the oil to be pumped through the lubricating pipes under the normal pump pressures of from '7 to 10 lbs. or more at temperatures materially below the cold test, that is, temperatures as low as minus 40 F., so that in addition to fully dewaxing the oil, I am able, by the process used herein, to increase its fluidity at temperatures below the cold test. Fluidity tests on this new oil at temperatures from plus 15 to minus 24 F. have proven that the fluidity of these paraffin base low cold test heavy cylinder stocks is greater than the fluidity of the so-called zero cold test lubricating stocks made from asphalt base or naphthene crudes under equal pressures.

My oil under low temperatures and under equal pressures provides the desired and necessary lubricating film on aircraft engines or the like and.

still flows freely and uniformly while lubricants manufactured from asphalt base crudes of the same viscosity at 210 F. at such low temperatures and equal pressures do not flow regularly, but become plastic and do not produce a film of its lubricant.

In producing my straight-run, unblended, fully dewaxed paraffin base lubricating oils from the crude oil, gasoline, kerosene, gas oils, cracking stocks and non-viscous neutrals, etc., are distilled overhead during the regular process of distillation in a continuous battery of stills or especially constructed tubular still equipped with fractionating equipment until in the last still of the continuous battery a lubricating stock of to viscosity at 210 F. is obtained. I treat this lubricating oil residual from the last still, which is operated at a temperature of from 590 to 600 F. after it has been stored and aged at an even temperature from 30 to 60 days with a minimum of 35 lbs. of 98% sulphuric acid to the barrel of oil at a temperature of from 100 to 125 F. The sludges produced by the sulphuric acid treatment are drawn from the agitators, and the clean acid ail is mixed with suitably prepared filtering clay using from .2 to 1 lb. of clay per gallon of oil and the mixture of filtering clay and oil is forced under pressure through a tubular pipe still heated to about 400 F. following which the mixture is cooled to F. minimum and mixed with a suitable diluent, such as naphtha, to produce a mixture having a gravity of 38-38 B. and is then forced through a pressure filter to remove the clay. The filtered oil is further diluted with naphtha or other diluent until the entire mixture has a specific gravity of 46 to 48 B. and is chilled to a temperature below 20 F. and preferably as low as minus 60 F. The chilled mixture is then centrifuged in super-centrifuges of the Sharpless or other type of machine to remove the wax and the fully dewaxed oil is re-run through the stills or specially designed tubular still at a temperature not exceeding 500 F. with a considerable amount of low pressure steam and the blending naphtha, as well as neutrals, are distilled overhead. These neutrals contain a certain percentage of light waxes and have a cold test of 20 to 30 F., while the remaining filtered heavy viscosity lubricating oils or bright stocks have a viscosity of from 55" at 210 F. to 200" at 210 F. Saybolt Universal viscosimeter, and have a cold test of 0 or below to 10 F.

To produce still lower cold test neutrals, I may blend together a mixture of 10 to 15% of the filtered lubricating stock, 70 to 80% of low boiling range naphtha and 10 to 15% of overhead neutrals and chill the mixture to a temperature as low as 40 to 60 F. below zero which mixture is then centrifuged to fully dewax the same and rerun through the still, giving a resulting cylinder stock having the viscosities and cold tests above noted and producing in the overhead neutrals a viscosity from 100 .to 300" at 100 F. having a cold test of zero to 10 F.

The presence of the light or crystalline type of waxes in the neutrals mixed with the normal amorphous wax content of these oils interferes with the separation of the congealed waxes from the chilled oil in the dewaxing step whether centrifugal separation or filter aid dewaxing is used, consequently in dewaxing these mixed wax bearing oils to produce 0 F. cold test it is necessary to increase the relative proportion of the amorphous or crystalline type of waxes so as to provide a wax content which may be substantially completely removed in one chilling and dewaxing step. The proportion of crystalline to amorphous waxes may be increased by subjecting the neutral oils to a severe heating or cracking which converts part of the amorphous wax to crystalline wax and provides a wax content which after dilution and chilling to -20 F. to -60 F. is suitable for filtering to remove the wax from the chilled oil and to produce a cold test of 0 to 10 F. in the dewaxed oil after removal of the diluent.

Another method of producing a cold test of substantially 0 F. in a distillate or neutral fraction containing mixed crystalline and amorphous waxes and normally having a cold test above 30 F. is to add to the oil approximately 10% of petrolatum, preferably obtained from the dewaxing of a residual fraction and therefore containing substantially all amorphous wax. The mixture of the distillate oil and petrolatum is then diluted with about 70% of naphtha or other low boiling point solvent and chilled to 20 to 60 F. and dewaxed by gravity subsidence or centrifugal separation to produce in the dewaxed oil after separation of the diluent a cold test of approximately 0 F.

A remarkable feature of these low cold test filtered lubricating oils, particularly the residual fraction, is their fluidity at temperatures below the cold point and their ability to flow under normal pump pressures at temperatures of plus 10 to minus 30 F. without previously heating the oil which permits the starting of automobile or aeroplane engines at low temperatures and in a much shorter time than is possible with any other lubricating oil, obtaining ample lubrication during the starting operation and substantially twice as many revolutions than with any other oils.

The oils produced according to this procedure have therefore the remarkable property never heretofore found in a lubricating oil of being able to flow under normal pump pressures and retaining their lubricating properties at temperatures of minus 40 F. to temperatures up to 350 F. or above, the latter temperature being an average operating temperature encountered in an internal combustion engine. While I have specified a cold test of zero or below as one of the specifications for my improved lubricating oil, it will be understood that an oil having a cold test below zero and the other properties herein enumerated, will be within the spirit of my invention which is to provide an unblended lubricating oil which retains its lubricating properties and is able to flow under normal pump pressures at temperatures of minus F. up to 350 or above.

Typical runs of the residual lubricating oil described above test as follows: (A. S. T. M. methods used) Cold test of 15 F. to plus 10 F. may be produced at will in one passage through the dewaxing equipment dependent upon the chilling temperature and the percentage of amorphous wax present.

While I have described the dewaxing of both residual and distillate fractions for the production of substantially 0 F. cold test lubricating oils, it will be understood that the residual fractions produce by far the better grade of lubricants, as the heat and vapor phase of the distillates causes decomposition of some of the valuable lubricating compounds present in the crude or residue and hence partially destroys the lubricating properties. The distillate fractions while not as valuable as the residual fractions still have considerable use as direct lubricants or as blending oils to be mixed with the residual oils for the production of special grades of lubricants.

The production of dewaxed paraffin base lubricating oils of either residual or distillate fractions,

having a cold test of 0 F. or below, is therefore a valuable contribution, particularly to the lubrication of automobile or aeroplane engines, or other machines requiring constant lubrication at low temperatures.

While I am aware that various modifications can be made in the process of producing my new lubricating oil as outlined above, it is to be understood I consider that I am the first to produce fully dewaxed unblended paraflin base lubricating oils having a viscosity of from at 210 to 200 at 210, and which will flow at pressures from '7 to 10 lbs. at temperatures as low as minus 40 F. and which retains its lubricating properties at high temperatures so as to permit its use under both high and low operating temperatures.

I desire, therefore, that the claim of the present application be interpreted as broadly covering this invention.

I claim:

The method of producing at 0 F. cold test distillate fraction of paraffin base lubricating oil from the neutral fraction normally produced as part of a paraffin base long residuum in dewaxing it to 0 F. cold test, which comprises mixing a portion of undewaxed residuum with said neutral fraction, diluting said mixture, chilling to -20 to F., removing the precipitated wax from said chilled oil, removing the diluent and separating the neutral and residual fractions, to provide 2. 0 F. cold test distillate fraction having a viscosity of to 300" at 100 F. and a 0 F. cold test residuum fraction stock having a. viscosity of 50 to 200" at 210 F.

ERWIN R. LEDERER. 

